The present invention relates to a pressure regulator for an adjustable pump having an adjustable member for regulating the amount of fluid delivered by the pump. The position of the adjustable member can be adjusted by two pistons of different diameters acting from opposite sides on the adjustable member and in which pressure of the fluid delivered by the pump is directed through a passage controlled by a control valve to one of the cylinder bores in which one of the pistons is closely guided.
A throttle is often arranged in the channel leading from the outlet of the pump to one of the pistons acting on the adjustable member through which fluid from the pump will flow to the aforementioned piston when the minimum pressure of response of the pressure regulator is lower than the pressure of the fluid delivered by the pump. The aforementioned throttle serves thereby to stabilize the adjustable member in a predetermined range of adjustment. A disadvantage of the aforementioned pressure regulators is that the mentioned arrangement of the throttle cannot always be constructively realized. In addition, it is not possible without further means to adjust the pump to an adjustable minimum stroke, as often desired, since this requires an adjustable abutment on one side of the regulator.